1. Field of the Invention
The present invention relates to pneumatic cushions and other fluid-filled cushions, and more particularly to a pneumatic cushion having a variable configuration with multiple chambers and a variable constriction of the flow between the chambers.
2. Related Art
Since the invention of the bicycle, the enjoyable activity of bicycle riding can become painful for both the buttocks and genitalia areas. Even before the invention of the bicycle, mankind looked for ways to comfortably support themselves during riding activities; the invention of the saddle is said to have occurred more than 3,000 years ago. The ‘pain-in-the-butt’ problem has been tackled with many different technologies over this lengthy period of time and has included leather, textile padding, springs, foam and gel cushions, and inflatable bladders. Problems with these technologies are widely varied (e.g., too costly to manufacture; too complicated to execute manufacturing & marketing; advertised benefits not easily achieved or realized; price points too expensive relative to competing products), but the one common occurrence is that they are mass-produced and not truly personalized to the individual's comfort requirements. Attempts to solve the problem boil down to a maxim that personalized comfort cannot be mass produced.
Since personalized comfort continues to be sought and inflatable bladders conform to a user, there are many styles of inflatable cushions for various types of seats, particularly including bicycle seats. However, most inflatable cushions provide one or more bladders that are in a fixed configuration even though the location of riders' ischium and pubic bones can vary dramatically based on the rider's size, gender and a number of other factors. Additionally, even when these fixed configuration bladders have multiple chambers that try to support a range of sizes and allow for the communication of the airflow, they do not have any variation in the constriction between the chambers. This lack of constriction may be important, particularly with bladders in a fixed configuration because a variation in the constriction could help provide more personalized comfort based on the particular rider's size, gender or some other factor (i.e., no variable valves or other mechanisms between the chambers).
It is already known to use a multi-chamber bladder with an extension tube that allows for airflow between the chambers and that also allows the chambers to be placed in various alternative configurations relative to each other, such as described in U.S. Pat. No. 5,558,395. However, merely permitting chambers to have different distances between them is not a solution to the problem of personalized comfort. There remains the issue of how much pressure should be in the chambers and what should be the flow rate of fluid between the chambers. For example, consider the possibility that there is sufficient pressure in two adjacent chambers in fluid communication with each other when a rider is in a steady state posture, such as when the rider is coasting, but if there is not enough constriction in the passageway(s) between the chambers when the rider is in a dynamic riding mode, the side that needs to provide support (which changes from one side to the other with the pedaling action of the rider) may merely collapse under the increased pressure of the rider and not provide the required support.
Additionally, when it comes to the particular use of the multi-chamber bladder design for bicycle seats, such as in U.S. Pat. No. 5,558,395, the extension tube is described as being useful for locating a release valve at an adjustable distance from the cushion, and there is no consideration given to the rate of the airflow between the cushions for the dynamic mode of operation. Another multi-chamber bladder may have two entirely separate bladders, each with its own filling valve and with no air passage between the bladders such as in U.S. Pat. No. 6,305,743. Other multi-chamber bladder designs have upper and lower bladders, such as in U.S. Pat. Nos. 608,857 and 611,377. The '377 Patent describes a valve mechanism between the bladders which can allow the downward flow of the air from the upper bladder to the lower bladder to pass more quickly than the return of the air from the lower bladder to the upper bladder. However, there is no allowance for the user to regulate the valve mechanism or otherwise vary the rate of flow between the bladders nor is there any ability for the user to change the configuration of the bladders.
It is clear that a multi-chamber bladder design by itself is not satisfactory to provide the kind of personalized comfort that has been sought after with inflatable bladder technology. One issue with previous attempts to provide support that conforms to the rider, including inflatable bladders as well as standard cushioning materials, is the fact that most designs are based on the same technology that is used for cushions that are optimized more for static conditions, such as cushions used for chairs or beds. In static conditions, there is no repeated pounding of the person's body against the cushioning material. More and more bicycle frames that are designed for off-road use take the dynamics of the road conditions into account in the design of the frame, and these frame designs include structural supports that are seen in other dynamic systems, like automotive vehicles and even aircraft, such as shock absorbers and designed frame deflection. However, unlike automotive vehicles and aircraft, where the pilots and drivers remain in a near steady-state seated position, a bike rider creates their own dynamics relative to the seat as they switch their power stroke from one leg to the other. Given this understanding of the combined problem of dynamics and personal comfort, it becomes more clear that the bladder designs that have typically been used for static seating arrangements could not possibly be satisfactory for a problem in which the particular bone structure of rider impacts the dynamics of the power stroke and the corresponding optimal support required from the seat.
Accordingly, there remains a need for an optimized cushion which provides the support that is required from the seat as a rider switches the power stroke from one leg to the other and which accounts for variations in personal anatomy.